The present invention relates to the field of turbomachines and more particularly to the field of injection manifold assemblies for turbomachines.
In the present context, the term “turbomachine” covers any machine in which energy can be transferred between a flow of fluid and at least one set of blades, such as for example a compressor, a pump, a turbine, or indeed a combination of at least two of these. Certain internal combustion turbomachines, such as gas turbines, turboshaft engines, turbofans or turbojets, or turboprops, enable the chemical energy of a fuel to be converted into mechanical energy by combustion of the fuel in the working fluid, with combustion taking place in a combustion chamber. Typically, such turbomachines comprise at least one compressor upstream from the combustion chamber and at least one turbine downstream from the combustion chamber and coupled to the compressor in order to actuate it by partial expansion of the working fluid as heated by the combustion of the fuel. Normally, a remainder of the thermal energy of the working fluid can then be recovered as mechanical energy by a jet nozzle and/or by at least one additional turbine coupled to a drive shaft. The terms “upstream” and “downstream” are defined relative to the normal flow direction of the working fluid through the turbomachine.
In order to ensure that combustion takes place uniformly within the combustion chamber, fuel is normally introduced therein via a plurality of injectors. When the combustion chamber is annular, these injectors are normally distributed around the combustion chamber and fed with fuel via at least one injection manifold assembly.
When starting the turbomachine, in order to be able to obtain a mixture that is sufficiently rich at least locally to enable ignition, even with a total flow rate of fuel that is initially small, it may be necessary, or at least advantageous, to restrict the feeding of fuel to only some of the injectors. Nevertheless, that normally requires injector manifold assemblies that are more complex, since they incorporate, in parallel with a main circuit, an auxiliary circuit for use when starting the turbomachine. This additional complexity makes fabricating injection manifold assemblies more difficult and more expensive and it also makes them more complicated to maintain.